PixInsight FITS files for AIP 4 Windows

[Starmangmh]

I recently purchased AIP 4 Windows and was trying to load an image saved in PixInsight.  Although I saved it as a FITS file in PI LE, AIP 4 Windows cannot open it.  Is there something I need to do or is there a specific form of FITS file I need to save it in so I can open it in AIP 4 Windows?  I know absolutely nothing about FITS files and am lost.

Thanks
Gary

[Juan Conejero]

Hello Gary,

Welcome to the weird world of non-conformant and/or partial FITS implementations. Please have a look at this document:

http://pleiades-astrophoto.com/pixinsight/FITS_support.html

That said, I am completely sure that the problem is NOT that AIP's FITS files don't conform to the FITS standard. So the problem must be that AIP isn't understanding some advanced usage of the FITS format that PixInsight LE does.

For example, PixInsight LE stores ICC profiles and image metadata into special FITS extensions. It saves also resolution and color space information as special FITS keywords. Many applications may be unable to manage these extensions, and perhaps they refuse loading PI's files for that reason.

Try the following:

- When saving as FITS in PixInsight, uncheck the "Embed ICC Profile" check box.

- Select the 16-bit signed integer sample format, which is the "baseline" FITS format, so to say.

- Avoid saving 64-bit floating-point and 32-bit integer FITS files, since these formats may not be supported by other applications.

If you are saving a 32-bit floating-point file and AIP doesn't load it, then the problem is most likely AIP's implementation of floating-point FITS support (it may conform to the standard, but perhaps it isn't flexible enough). Then you may try the signed 32-bit integer sample format instead (which will preserve the whole floating-point accuracy).

I'd appreciate if you could post a link to some file(s) that you are having trouble with.

Thank you very much for your interest.

Juan

[Starmangmh]

Hi Juan,
    I tried what you said and it still won't load.  The error message I receive is... FITS Header Error: naxis=3 and naxis3 not = 1

When I pull up the FITS header in PI LE, under SIMPLE it says...
Value - T      Comments - File does not conform to FITS standard

Does this help any?

Gary

[Juan Conejero]

Hi Gary,

I guess I know what's happening: AIP doesn't support RGB color images stored as single FITS files. This is because the error message you're receiving does not make sense at all (if NAXIS is 3, then NAXIS3 cannot be equal to 1).

On the other hand, it should read "file does conform to FITS standard", actually, if the value of SIMPLE is T (true).

Could you please send the original file generated by PixInsight through the NASA's FITS verifier at:

 http://fits.gsfc.nasa.gov/fits_verify.html

and tell me if there is some error reported ?

If NASA's FITS verifier tells the file is correct, then the problem is in AIP.

Thank you.

[Juan Conejero]

Gary,

By the way, you can send a small crop of an image to the FITS verifier (define a small preview and use Preview > Make Image, for example, and save the new window as a FITS file); you don't need to send a huge file if you have bandwidth limitations.

Juan

[Starmangmh]

Hi Juan,
    Thanks for the link.  I ran a 25% downsampled image through the FITS Verifier and it came up with 0 errors so maybe you are right in that AIP won't take RBG images.  I'll have to read more in the book to see what's up with this.  Thank you for helping me find where the problem is.  I mainly purchased this product for the book more than the program.  I really like PI LE and am looking forward to more program updates and for the commercial version to come out.

Thanks
Gary

[Juan Conejero]

Hi Gary,

Thank you for your nice words. I'd appreciate any insight into why AIP isn't loading PI's color FITS files, so if you discover anything, please pass it around!

A first version of PixInsight Standard is due after Summer; however I wouldn't be so optimistic. Say early Winter. We are working very hard in the application now, but some problems in porting extremely complex code to new development frameworks are slowing us down. The final thing will worth all the wait for sure.

Juan

[Starmangmh]

Juan,
Okay, I've got it now.  I extracted the 3 channels in PI LE and saved them seperately, then tried to open in AIP and they opened just fine.  I'll still read to see if it's possible to open an RBG FITS image, but at least I can get the channels to load.  Thanks for all your help.

Gary